This section provides background information related to the present disclosure which is not necessarily prior art.
Electromagnetic-based navigation procedures include a surgeon using a navigation system to track a position of a surgical instrument in a three dimensional (3-D) space. In addition to the surgical instrument, the navigation system also includes a localizer and a processor. The localizer generates electromagnetic fields (or first signals), which are detected by the surgical instrument. The surgical instrument generates and/or outputs second signals in response to the first signals. The processor then determines a position of the surgical instrument based on the second signals.
The navigation system can assist in determining a location of a tracked device on a pointer probe and/or on a surgical instrument, such as a scalpel, a catheter, a suction device, or a deep brain stimulation probe. A pointer probe may be used to track a position of an instrument not having a tracking device. A tracked device may refer to the pointer probe, the surgical instrument or a device on the pointer probe or the surgical instrument. The position of the tracked device can be determined relative to a subject (e.g., a patient). The position of the tracked device can be illustrated on a display relative to the subject by superimposing an icon or image of the tracked device on an image of the subject.
Image data of the subject is often acquired for display prior to, during, and/or after a procedure on the subject. An image of the subject and the corresponding image data can be registered to the subject. The image data can define a first three-dimensional space (or image space). The subject can define a second three-dimensional space (or physical space) to which the image data is registered. Registration can be performed using multiple processes.
An electromagnetic (EM) navigation system can be used to acquire or determine navigation information, including tracked locations of various tracking devices and relative locations to registered image data. In an EM navigation system, EM fields are generated by a localizer and sensed by one or more tracking devices. The localizer can be positioned near or relative to the subject space. The tracking devices can be positioned on or in association with a surgical instrument. The EM fields can be affected by conductive or magnetic materials located in an area of the EM fields. Examples of conductive materials are metals, conductive polymers, and impregnated polymeric materials. An example of a magnetic material is soft ferromagnetic iron.